Modern ICs are often relatively complex. The trends in semiconductor design and manufacturing point to increased complexity of ICs in the future. Although manufacturers strive for, and make, continued improvement in the fabrication processes of ICs, defects occur nevertheless. As a consequence of the defects, manufacturing yields decrease. Because complex IC dies have a relatively high cost to design and manufacture, even a relatively small decrease in yield can prove costly.
To reduce the negative impact of defects on yield, designers sometimes include redundancy features in ICs. Through redundancy, one may substitute an operational block or circuit for a defective one. Conventional approaches to providing redundancy, however, introduce additional complexity themselves. A need therefore exists for providing cost-effective redundancy in ICs.